The invention relates to a water tight door and more particularly to a water tight bulkhead door on a ship.
Traditionally water tight bulkhead doors were heavy and utilized grooves or knife edges and flat gaskets to provide high pressure areas on the flat gaskets to provide an effective seal. A linkage type hinge or a slotted hinge assembly is used so the door can freely rotate to the closed position, at which time a lateral door movement is introduced by a dogging mechanism, pulling the entire door perimeter into simultaneous high pressure knife edge and gasket interaction. Consequently to seal the door requires that high closing forces be provided by a dogging mechanism, which includes heavy linkage that slide movable wedges over fixed wedges to create the lateral motion needed for sealing. Distortion of the doors and bulkheads created by such things as dynamic loading of the hull, improper door installation techniques and damage to the frame or door panel either increase the dog loading required to create a seal or form gaps between the knife edge and gasket so that watertightness is lost. The dogging mechanism is subjected to high frictional loads and rapid wear, resulting in frequent adjustment and leaking doors.